128 



of the straw they make preparations for passing the winter, and even 

 for their escape from the straw the following year. This last is done 

 by cutting the straw circularly on the inside nearly severing it a 

 short distance, varying from one half inch to one inch from the 

 ground. Fig 



■ III 



I, c. 



If the wheat were growing wild, the winter 

 winds would cause the stalk to break off at 

 this point ; and thus the insect after it had 

 reached the adult stage in the following year 

 could easily escape ; while but for this cut, it 

 would be very liable to be imprisoned within 

 the straw. But under ordinary circumstances 

 the straw is cut by the reaper before it is 

 broken off at this point, and consequently 

 that breaking off does not occur. If, how- 

 ever, tliere is a strong wind just before the 

 harvest and after the straws have been cut 

 in this manner by the insects, they are very 

 liable to break off; the lodging of the grain 

 may, therefore, be largely due to the in- 

 juries of this insect. In one field just be- 

 fore the harvest I observed a large number 

 of isolated straws lying in a horizontal po- 

 sition, there was not the general breaking 

 down of the grain characteristic of wind and rain ; but distributed 

 through the grain that was standing there were a large number of 

 isolated straws that were lodged. A careful examination showed 

 that this breaking down of the grain, in 45 per cent of the cases, 

 was directly due to the injuries of this in.sect. In many cases the 

 straws had been broken off a considerable distance above the 

 ground, and before the larva had made the characteristeric circu- 

 lar cut near the root. An examination of these straws showed 

 that the larva had eaten all or nearly all of the softer inner part 

 of the straw for a short distance, thus making a weak place which 

 was easily broken. As a rule, however, the larva obtains the 

 greater part of its nourishment by tunnelling the joints of the 

 straw and does not eat enough of the straw in any place to cause 

 it to break until they make the circular cut near the ground 

 described above. 



After the circular cut has been made, the larva fills the cavity 

 of the straw just below it for a short distance with a plug of bor- 



FlG. I. — Base of an in- 

 fested straw, a, cocoon ; 

 b, plug of borings ; c, cir- 

 cular cut d, scattered bor- 

 ings. 



